For 100 years, there has been no change in the basic structure of the electrical power grid. Experiences have shown that the hierarchical, centrally controlled grid of the 20th Century is ill-suited to the needs of the 21st Century. To address the challenges of the existing power grid, the new concept of smart grid has emerged. The smart grid can be considered as a modern electric power grid infrastructure for enhanced efficiency and reliability through automated control, high-power converters, modern communications infrastructure, sensing and metering technologies, and modern energy management techniques based on the optimization of demand, energy and network availability, and so on. While current power systems are based on a solid information and communication infrastructure, the new smart grid needs a different and much more complex one, as its dimension is much larger. This paper addresses critical issues on smart grid technologies primarily in terms of information and communication technology (ICT) issues and opportunities. The main objective of this paper is to provide a contemporary look at the current state of the art in smart grid communications as well as to discuss the still-open research issues in this field. It is expected that this paper will provide a better understanding of the technologies, potential advantages and research challenges of the smart grid and provoke interest among the research community to further explore this promising research area.

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Smart Grid Technologies: Communication Technologies and Standards

The wave energy is having more and more interest and support as a promising renewable resource to replace part of the energy supply, although it is still immature compared to other renewable technologies. This work presents a complete analysis of the wave energy technology, starting with the characterisation of this global resource in which the most suitable places to be exploited are showed, and the classification of the different types of wave energy converters in according to several features. It is also described in detail each of the stages that are part in the energy conversion, that is, from the capture of the energy from the waves to the extraction of a proper electrical signal to be injected to the grid. Likewise, existing offshore energy transmission alternatives and possible layouts are described.

Review of wave energy technologies and the necessary power-equipment

Traditional power grids are being transformed into smart grids (SGs) to address the issues in the existing power system due to uni-directional information flow, energy wastage, growing energy demand, reliability, and security. SGs offer bi-directional energy flow between service providers and consumers, involving power generation, transmission, distribution, and utilization systems. SGs employ various devices for the monitoring, analysis, and control of the grid, deployed at power plants, distribution centers, and in consumers' premises in a very large number. Hence, an SG requires connectivity, automation, and the tracking of such devices. This is achieved with the help of the Internet of Things (IoT). The IoT helps SG systems to support various network functions throughout the generation, transmission, distribution, and consumption of energy by incorporating the IoT devices (such as sensors, actuators, and smart meters), as well as by providing the connectivity, automation, and tracking for such devices. In this paper, we provide a comprehensive survey on the IoT-aided SG systems, which includes the existing architectures, applications, and prototypes of the IoT-aided SG systems. This survey also highlights the open issues, challenges, and future research directions for the IoT-aided SG systems.

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Internet of Things-Aided Smart Grid: Technologies, Architectures, Applications, Prototypes, and Future Research Directions

This paper presents a diagnostic and prognostic condition monitoring method for insulated-gate bipolar transistor (IGBT) power modules for use primarily in electric vehicle applications. The wire-bond-related failure, one of the most commonly observed packaging failures, is investigated by analytical and experimental methods using the on-state voltage drop as a failure indicator. A sophisticated test bench is developed to generate and apply the required current/power pulses to the device under test. The proposed method is capable of detecting small changes in the failure indicators of the IGBTs and freewheeling diodes and its effectiveness is validated experimentally. The novelty of the work lies in the accurate online testing capacity for diagnostics and prognostics of the power module with a focus on the wire bonding faults, by injecting external currents into the power unit during the idle time. Test results show that the IGBT may sustain a loss of half the bond wires before the impending fault becomes catastrophic. The measurement circuitry can be embedded in the IGBT drive circuits and the measurements can be performed in situ when the electric vehicle stops in stop-and-go, red light traffic conditions, or during routine servicing.

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In Situ Diagnostics and Prognostics of Wire Bonding Faults in IGBT Modules for Electric Vehicle Drives

Due to the increasing importance of power electronic components in automobiles, it becomes necessary to consider their reliability. This applies especially to hybrid electrical vehicles (HEV) where a malfunction of the power electronics may prevent the vehicle to operate. Of paramount importance for the reliability of power electronics is the component operating temperature and temperature cycling. This paper deals with the development of an advanced simulation tool which is capable of determining the component temperature of a three-phase converter over long mission profiles. In addition, the expected converter reliability is calculated. To accomplish this, losses in the semiconductors and dc-link capacitors are determined first. Next, this loss data is fed into a thermal model to compute the component temperatures, for the whole mission profile. As basis for the reliability computation, failure-rate catalogs, such as Military Handbook 217F or RDF 2000, are used. Also an approach using simple formulas for lifetime prediction is presented. According to failure-rate catalogs, temperature cycles are of particular importance for the reliability of power semiconductors. A novel algorithm, detecting all relevant temperature cycles within the computed temperature curve is developed. Finally, the applicability and significance of the presented reliability prediction methods is assessed.

Reliability Prediction for Inverters in Hybrid Electrical Vehicles

Communication methods for smart metering pose a number of unique challenges driven from the demand for a unique communication network that can communicate with some 28 million devices in the UK with near real-time latency In this paper an overview of communication methods for Smart Metering is presented, focusing towards ”The Last Mile” of the communication network connected to the metering device The need for robust low-bandwidth communications is a core requirement due to the possible interference from consumer products operating in unlicensed frequency bands Investigations towards both wired and wireless technologies are performed and conclusions indicate that Power Line Communication (PLC) is becoming a low cost method to communicate with metering devices Additionally, it can operate in relatively low bandwidth channels in the sub 100kHz region of the spectrum An analytical approach towards analysis of coding schemes for OFDM based PLC systems is performed Through investigation of current state of the art coding techniques we present a series of performance markers for (PLC) at low-bit rates when degraded with various channel effects Results show that (PLC) has real potential for Smart Metering networks where high-levels of interference are present from existing communication technologies

Assessment of communication methods for smart electricity metering in the U.K.

This paper presents a Modified Perturb & Observe (P&O) Maximum power point tracking (MPPT) algorithm using fuzzy logic-based variable step size to overcome some of the limitations associated with the conventional P&O MPPT tracking method to improve the transient response and reduce the steady-state terminal voltage oscillations. The proposed MPPT algorithm was implemented and tested on an indoor emulated PV source that is constructed from a conventional solar panel and a DC power supply, a boost DC-DC converter and a dSPACE-based MPPT controller. The advantage of implementing this testing platform for MPPT is easy implementation and indoor testing of MPPT algorithms and DC-DC power converters. Thus, dependency on atmospheric conditions such as irradiance level can be avoided. Details of the emulated PV source mathematical model and electrical characteristics, the proposed MPPT algorithm via dSPACE, simulation and test results were presented in the paper.

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A Fuzzy Logical-Based Variable Step Size P&O MPPT Algorithm for Photovoltaic System

A fast power losses calculation method for long real time thermal simulation of IGBT module for a three-phase inverter system is presented in this paper. The speed-up is obtained by simplifying the representation of the three-phase inverter at the system modelling stage this allows a inverter system to be simulated predicting the effective voltages and currents whilst using large time-step. An average power losses is calculated during each clock period, using a pre-defined look-up table, which stores the switching and on-state losses generated by either direct measurement or automatically based upon compact models for the semiconductor devices. This simulation methodology brings together accurate models of the electrical systems performance, state of the art-device compact models and a realistic simulation of the thermal performance in a useable period of CPU time and is suitable for a long real time thermal simulation of inverter power devices with arbitrary load. Thermal simulation results show that with the same IGBT characteristics applied, the proposed model can give the almost same thermal performance compared to the full physically based device modelling approach

A fast power loss calculation method for long real time thermal simulation of IGBT modules for a three-phase inverter system

MPPT algorithm test on a photovoltaic emulating system constructed by a DC power supply and an indoor solar panel

Temperature and temperature variation cycles of insulated gate bipolar transistors (IGBTs) are important variables for reliability assessment of inverter power module (IPM) applied in hybrid vehicles. Conventional electro-thermal (ET) simulation based on physics device model has been considered as an accurate method, but it is difficult to conduct a long real-time (over 10 min) thermal simulation as required in hybrid vehicles. In this study, a fast ET simulation model for long real-time thermal simulation of three-phase IGBT IPMs is presented in which the consideration of inverter/motor power train modelling, determination of simulation time step, calculation of temperature-dependent power losses as well as thermal network are discussed in detail. The advantage of the proposed simulation model is the IGBT temperature and variation cycle with power cycles of vehicles can be simulated at a fast speed without significant loss of accuracy. Device temperature over 10 min of real-time operation for a three-phase IGBT IPM has been simulated and validated by an experimental test.

Zhongfu Zhou

Papers

Assessment of communication methods for smart electricity metering in the U.K.

A Fuzzy Logical-Based Variable Step Size P&O MPPT Algorithm for Photovoltaic System

A fast power loss calculation method for long real time thermal simulation of IGBT modules for a three-phase inverter system

MPPT algorithm test on a photovoltaic emulating system constructed by a DC power supply and an indoor solar panel

High-speed electro-thermal simulation model of inverter power modules for hybrid vehicles